Luckily for me, I rarely run into people from my past - quite rarely (knock on wood). I guess it helps tremendously to not get out much - the less you're "out there", the less chances are that you will have such awkward experiences. I don't write this to give people "advice" or anything - just making a standard observation that very much applies to my particular circumstances.
However - I've thought/wondered if I have actually been in the same places as people from my past more often than I realize - and we just failed to recognize each other. For people who knew me in prior decades, it's pretty easy to miss me, I guess; though I was never a slim person, I weigh a ton more than I used to weigh. And there have been other, perhaps less-favorable changes to my appearance. I suppose that I don't look much like people who knew me a long time ago expect me to look; the adult me doesn't have the image that some people may have projected for me.
I'm thankful that there haven't been too many times when I've had to face those awkward, excruciating moments when I bump into some old acquaintance - and my mind races with feelings of embarrassment about the changes to my appearance, and try my best to get the encounter over with before they ask me "What are you doing these days?"
Over the years, I've definitely had to face a few such moments, though. About 10 months ago, I was absolutely shocked when a man approached me who turned out to be an old schoolmate from elementary school. To the best of my knowledge, we hadn't seen each other since June 1985 - yet, he somehow recognized me as though June 1985 was only yesterday. Luckily, the "reunion" was pretty brief - and ended before he could see more evidence of what a complete psychological wreck I was, or the dreaded "So what are you doing these days?" question was asked.
And not too long before that encounter, I'm reasonably sure that I almost literally ran into another elementary school classmate - someone who I last saw in 1995 (long after elementary school). Yet - this person politely acknowledged me without recognizing me at all. It was a surreal experience; in retrospect, it's pretty comical how much of a "close call" this experience was...how I hid "in plain sight" of this person. I guess sometimes, a 90-pound weight-gain comes in handy!